<script>
export default {
  name: "v-modelTheory",
  data() {
    return {
      msg1:'',
      msg2:'',
    }
  }

}
</script>

<template>
  <div>
      <input v-model="msg1">
      <input :value="msg2" @input="msg2 = $event.target.value">
  </div>
</template>

<style scoped>
input {
  margin: 10px;
  display: block;
}
</style>